Devices and methods for providing a smart load for an electricity supply network are described in an earlier published international PCT patent application WO 06/28709A2 which is hereby incorporated by reference. This published patent application describes refrigerators and draws an analogy with pumping water into a tank. However, the application does not consider other types of devices having other operating constraints. Thus, electrical load shedding in response to changes in electrical supply network mains line frequency is known and is based on devices such as water heaters and refrigerators. Moreover, automatic start-up after an electrical black out is also known.
At present, the World consumes circa 80 million barrels of oil per day. A significant portion of this oil is employed for transport, for example for automobiles, trucks, ships and aircraft. Petroleum represents an extremely concentrated form of energy which is convenient to employ in mobile apparatus, for example automobiles. However, there is a desire to employ electrical power for road transport in the future, wherein the electrical power is ideally generated from renewable energy sources. In practice, the electrical power is more likely to be derived from burning coal in coal-fired power stations (creating greenhouse gases) and from nuclear reactors (generating dangerous long-lived radioactive waste). Such coal-fired power stations and nuclear power stations are known to be capable of coping with a steady baseline load but have difficulty coping with rapidly fluctuating demand. Moreover, when a large portion of society employs personal electric transport, it is expected that electricity supply demands will be much greater in future with greater temporal fluctuations in such electrical demand.
For example, rapid battery chargers for electric vehicles are each expected to consume several kiloWatts (kW) of electrical power from electrical supply networks when charging batteries of these vehicles. Such a magnitude of consumption dwarfs an amount of power consumed by refrigerators and similar appliances. However, methods of controlling heating and cooling in refrigerators are quite inappropriate when charging batteries, for example charging lithium batteries or ultra capacitors, which have very different requirements. For example, a company EEstor Inc. is alleged to have recently developed an ultracapacitor based upon barium titanate material in nano-particle form offering an energy storage density in excess of 300 Wh/kg with unlimited number of recharge/discharge cycles; if such battery technology can be implemented in an economical form, it represents a major breakthrough in electric road transport paving a way for a transition from combustion engine road transport to electric road transport.
Some processes, for example battery charging processes, are both energy intensive and complex, namely requiring carefully controlled sequences of charging power variations to complete for maintaining optimal battery lifetime. Such charging processes do not fall within constraints appropriate for controlling refrigerators pursuant to the international PCT patent application WO 06/28709A2. In respect of battery charging, electrical supply line-frequency responsive processes that disconnect electrical devices at times of grid stress are undesirable. Similarly, washing machines and dishwashers respond badly to being disconnected for periods from their electrical supply network; for example, dish washers are required to achieve a sufficiently high temperature to ensure that microbes are destroyed during dish washing, and clothes can be damaged if left for unnecessarily prolonged periods at elevated temperatures.
There thus arises a need for alternative types of smart responsive electrical loads for use in stabilizing electrical supply networks which are able to cope with complex energy consuming processes which employ complex sequences of steps in contradistinction to simple on-off devices, for example refrigerators.